Activator solid support for metallocene catalysts in the polymerization of olefins, a process for preparing such a support, and the corresponding catalytic system and polymerization process

ABSTRACT

Activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminium and/or magnesium Lewis-acid sites of formula:  
                 
 
     groups coming from a functionalization agent having reacted with —OH radicals carried by the base particles of the support, the functionalization reaction having been followed by a fluorination reaction.  
     The catalytic system according to the invention comprises (a) a metallocene catalyst, which has, if required, been subjected to a prealkylation treatment; (b) a cocatalyst; and (c) an activator solid support for metallocene, as defined above, it being possible for the cocatalyst (b) to be absent if the metallocene catalyst (a) has been prealkylated.

[0001] The present invention relates to an activator solid support for metallocene catalysts used for the polymerization of olefins, to a process for preparing such a support, to the corresponding catalytic system and to the suspension or gas-phase polymerization of olefins using such a catalytic system.

[0002] It is well known to (co)polymerize ethylene and α-olefins in the presence of a metallocene/aluminoxane catalyst system. The first very active catalytic system of this type that was discovered is that based on zirconocene: Cp₂ZrCl₂/aluminoxane. Metallocene/aluminoxane catalyst systems are soluble in the polymerization medium. The extension of research in this field has led to the discovery of other metallocene catalysts, such as bridged metallocenes which are capable, in the case of the copolymerization of ethylene with α-olefins, of leading to better uniformity in the distribution of the comonomers in the molecular chains.

[0003] However, aluminoxanes, in particular methylaluminoxane which is the most commonly used, have the drawbacks of being expensive and unstable substances which are partly responsible for the poor morphology of the polymers, a situation which causes fouling of the reactors and which makes the conveying process very complicated.

[0004] The Filing Company has sought to solve this problem for the purpose of providing a metallocene-based catalytic system, which is active for the polymerization of olefins and does not use aluminoxane, or uses less aluminoxane than in the past.

[0005] It is now accepted that a metallocene complex has a cationic nature in its active form. This has been confirmed by several spectroscopic methods and by the equivalence of the properties of two polymers, one produced by the metallocene/aluminoxane system and the other produced by metallocene/stable cationic salt systems. The role of the aluminoxane is assumed to be the alkylation of the metallocene, the activation of the methylated species by the formation of a cationic complex and the stabilization of this active species. Many non-coordinating counteranions have been proposed for replacing the aluminoxane in its activator role [J. Ewen, M. Elder, R. Jones, L. Haspeslagh, J. Atwood, S. Bott and K. Robinson, Makromol. Chem. Macromol. Symp. 48/49, 253 (1991) and M. Bochmann and S. Lancaster: Organometallics, 12, 633 (1993)].

[0006] The Filing Company has discovered that the counteranion of the active cationic complex could consist of a solid support, advantageously having a defined and controlled structure comparable to that of the supports employed in conventional Ziegler-Natta catalysis in order to allow physical development of the polymerization, the said support being functionalized in order to create acid sites which activate the metallocene without complexing it.

[0007] The solid support according to the invention, as defined below, constitutes an activator support which has made it possible to reach levels of. activity, in the polymerization of olefins, at least equal to, but often greater than, the activity displayed by a purely homogeneous system.

[0008] The subject of the present invention is therefore firstly an activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminium and/or magnesium Lewis-acid sites of formula:

[0009] groups coming from a functionalization agent having reacted with —OH radicals carried by the base particles of the support, the functionalization reaction having been followed by a fluorination reaction.

[0010] The direct use of aluminium and/or magnesium fluorides presents difficulties which are barely surmountable in terms of forming a support having suitable particle-size and porosity properties.

[0011] The porous mineral oxides are advantageously chosen from silica, alumina and mixtures thereof.

[0012] The porous mineral oxide particles preferably have at least one of the following characteristics:

[0013] they include pores having a diameter ranging from 7.5 to 30 nm (75 to 300 Å);

[0014] they have a porosity ranging from 1 to 4 cm³/g;

[0015] they have a specific surface area ranging from 100 to 600 m²/g; and

[0016] they have an average diameter ranging from 1 to 100 μm.

[0017] Before it is modified, the support has —OH radicals on its surface, in particular from 0.25 to 10, and even more preferably from 0.5 to 4 —OH radicals, per nm². After it has been modified, the said support has as many at least partially fluorinated aluminium and/or magnesium Lewis-acid sites per nm².

[0018] The support may be of various kinds. Depending on its nature, its state of hydration and its ability to retain water, it is possible to make it undergo dehydration treatments of greater or lesser intensity depending on the desired surface content of —OH radicals.

[0019] Those skilled in the art may determine, by routine tests, the dehydration treatment that should be applied to the support that they have chosen, depending on the desired surface content of —OH radicals.

[0020] For example, if the support is made of silica, which is in accordance with a preferred embodiment of the invention, the silica may be heated between 100 and 1000° C. and preferably between 140 and 800° C., with purging by an inert gas such as nitrogen or argon, at atmospheric pressure or under a vacuum, for example of an absolute pressure of 1×10⁻² millibars, for at least 60 minutes, for example. For this heat treatment, the silica may be mixed, for example, with NH₄Cl so as to accelerate the dehydration.

[0021] If this heat treatment is between 100 and 450° C., it is conceivable to follow it with a silanization treatment. This kind of treatment results in a species derived from silicon being grafted on the surface of the support in order to make this surface more hydrophobic. This silane may, for example, be an alkoxytrialkylsilane, such as methoxytrimethylsilane, or a trialkylchlorosilane, such as trimethylchlorosilane or triethylchlorosilane.

[0022] This silane is generally applied to the support by forming a suspension of this support in an organic silane solution. This silane may, for example, have a concentration of between 0.1 and 10 mol per mole of OH radicals on the support. The solvent for this solution may be chosen from linear or branched aliphatic hydrocarbons, such as hexane or heptane, alicyclic hydrocarbons, optionally substituted, such as cyclohexane, and aromatic hydrocarbons, such as toluene, benzene or xylene. The treatment of the support by the silane solution is generally carried out between 50° C. and 150° C., for 1 to 48 hours, and with stirring.

[0023] After silanization, the solvent is removed, for example, by siphoning or filtration, the support then being washed, preferably thoroughly, for example using 0.3 l of solvent per gram of support.

[0024] The surface —OH radical content of the support may be assayed using known techniques such as, for example, by reacting an organomagnesium compound such as CH₃MgI with the support and by measuring the amount of methane given off [McDaniel, J. Catal., 67, 71 (1981)]; by reacting triethylaluminium with the support and by measuring the amount of ethane given off [Thesis of Véronique Gachard-Pasquet, Université Claude Bernard, Lyon 1, France, 1985, pages 221-224].

[0025] According to the present invention, the said at least partially fluorinated aluminium and/or magnesium Lewis-acid sites are formed by the reaction of —OH radicals carried by the support base particles with at least one functionalization agent chosen from:

[0026] compounds of formula (I):

Al(R¹)₃   (I)

[0027] in which the R¹ groups, which are identical or different, each represent a C₁-C₂₀ alkyl group;

[0028] compounds of formula (II):

Mg(R²)₂   (II)

[0029] in which the R² groups, which are identical or different, each represent a C₁-C₂₀ alkyl group; and

[0030] compounds of formula (III):

[0031] in which:

[0032] the R³ groups, which are identical or different, each represent a C₁-C₁₂ alkyl group or a C₁-C₁₂ alkoxy group;

[0033] the R⁴ groups, which are identical or different, each represent a C₁-C₁₂ alkyl group or a C₁-C₁₂ alkoxy group;

[0034] Y represents Al or Si, m having a-value of 2 if Y=Al and 3 if Y=Si; and

[0035] n has a value of 0 or is an integer from 1 to 40, n preferably having a value of 0 or being an integer from 1 to 20;

[0036] compounds of formula (IV):

[0037] in which:

[0038] the R⁵ groups each represent a C₁-C₈ alkyl group; and

[0039] p is an integer from 3 to 20,

[0040] the said functionalization reaction having been followed by a fluorination reaction.

[0041] By way of examples of compounds (I), mention may be made of those in which the R¹ groups represent methyl, ethyl, butyl and hexyl, it being possible for the aluminium to carry 1, 2 or 3 different groups; a preferred compound (I) is triethylaluminium.

[0042] By way of examples of compounds (II), mention may be made of those in which R² represents methyl, ethyl and butyl; a preferred compound (II) is (n-butyl)(sec-butyl)magnesium.

[0043] By way of examples of compounds (III), mention may be made of dibutoxyaluminoxytriethoxysilane (C₂H₅O) ₃Si—O—Al—(OC₄H₉) ₂, tetraisobutyldialuminoxane (iBu)₂Al—O—Al(iBu)₂ and linear alkylaluminoxane oligomers, in particular those in which R³ and R⁴ are methyl groups.

[0044] Compounds (IV) are cyclic alkylaluminoxane oligomers; in particular, mention may be made of those in which R⁵ is a methyl group.

[0045] The present invention also relates to a fluorinated functionalized support, as described above, in the state in which it is pre-impregnated with a metallocene catalyst, the said metallocene catalyst having been subjected, if required, to a prealkylation treatment carried out before or after the said support has been pre-impregnated.

[0046] The present invention also relates to a process for preparing an activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide and carry, on the surface, —OH radicals, undergoes functionalization by using a functionalization agent capable of grafting aluminium and/or magnesium Lewis-acid sites on the said particles; the said support particles thus grafted are then subjected to a fluorination treatment.

[0047] In order to implement this process, it is possible to use the support particles such as those described above and the functionalization agents such as those described above.

[0048] In a preferred method of implementing this process, the functionalization is carried out by treating a suspension of the said particles in a solvent medium with the said functionalization agent at a temperature ranging from −150° C. to +150° C. for a period of time ranging from 1 minute to 12 hours, and then by recovering the grafted particles after washing. The solvent is especially chosen from aliphatic, alicyclic and aromatic hydrocarbons, and more preferred temperature and time conditions are from 30 to 100° C. and from 1 to 3 hours. In particular, from 0.5 to 20 mmol of functionalization agent per g of particles are used.

[0049] After functionalization, a heat treatment in an inert gas (such as argon or nitrogen) may optionally be carried out, preferably in a bed fluidized by the said inert gas, the said treatment being intended to remove the alkoxy groups present on the surface, which groups could come from the functionalization agent carrying R³ and/or R⁴ alkoxy radicals. This heat treatment, or pyrolysis, is advantageously carried out at approximately 200-600° C. for approximately 1-10 hours. If the treatment were not carried out, the alkoxy groups could be the cause of water forming by reaction with oxygen during an oxidation treatment which may be intended before the final fluorination. This is because it is desirable to remove any trace of water since water is likely to adversely affect or poison the solid support.

[0050] The oxidation treatment indicated above may advantageously consist of a heat treatment of the functionalized support particles, in a bed fluidized by oxygen, for example at 200-600° C. for 1-10 hours. This treatment makes it possible to increase the acidity of the surface of the support and, consequently, the performance of the catalytic system.

[0051] The radicals R¹, R², R³, R⁴ and R⁵ are at least partially replaced by F during the final fluorination step. The fluorination treatment may be carried out by bringing the functionalized support particles into contact with gaseous hydrofluoric acid, if necessary after heat treatment in an inert gas and/or after oxidation, this contacting step being carried out for a period of time ranging from 1 minute to 24 hours, at a temperature ranging from 20 to 800° C.; however, the hydrofluoric acid may advantageously be replaced by (NH₄)₂SiF₆, in which case the functionalized support particles are mixed with powdered (NH₄)₂SiF₆, if necessary after heat treatment in an inert gas and/or after oxidation; the actual fluorination treatment with (NH₄)₂SiF₆ consists especially in gently fluidizing the aforementioned mixture of support particles and (NH₄)₂SiF₆ with an inert gas, such as argon or nitrogen, and in carrying out a heat treatment at a temperature of approximately 300 to 500° C. for approximately 1 to 10 hours. In general, especially from 1 to 5% by weight, in particular 3 to 5% by weight, of fluorine with respect to the said support particles are used for the fluorination (above the value of 5% by weight, the support undergoes degradation).

[0052] The present invention also relates to a catalytic system for the polymerization of olefins, comprising:

[0053] (a) a metallocene catalyst, which has, if required, been subjected to a prealkylation treatment;

[0054] (b) a cocatalyst; and

[0055] (c) an activator solid. support for metallocene, as defined above or prepared by the process as defined above,

[0056] it being possible for the cocatalyst (b) to be absent if the metallocene catalyst (a) has been prealkylated, it being possible for the support (c) to have been impregnated with the metallocene catalyst (a), which catalyst has, if required, been subjected to a prealkylation treatment carried out either before or after the said support has been pre-impregnated.

[0057] The metallocene catalyst (a) generally consists of a compound of formula (V):

ML_(x)   (V)

[0058] in which:

[0059] M represents a transition metal belonging to Group 4b of the Periodic Table of Elements according to the Handbook of Chemistry and Physics, 61st edition;

[0060] L represents a ligand coordinated to the transition metal, at least one ligand L being a group having a cycloalkadienyl-type backbone; and

[0061] x is equal to the valency of the transition metal, the ligands L, the number of which is equal to the valency of the transition metal M, being identical or different.

[0062] In particular, M is Ti, Zr or Hf.

[0063] The expression “group having a cycloalkadienyl-type backbone” should be understood to mean the cycloalkadienyl group itself or a substituted cycloalkadienyl group.

[0064] Preferably, a cycloalkadienyl group is a cyclopentadienyl group.

[0065] When the compound of formula ML_(x) contains at least two groups having a cycloalkadienyl-type backbone, at least two of these groups may be linked together by a divalent radical. Each divalent radical may be an alkylene radical, such as the methylene radical (—CH₂—), the ethylene radical (—CH₂CH₂—) or the trimethylene radical (—CH₂CH₂CH₂—), it being possible for this alkylene radical also to be substituted, for example by at least one hydrocarbon group, such as the isopropylidene-radical; the divalent radical may also be a silylene (—SiH₂) group, optionally substituted, for example by at least one hydrocarbon group, as is the case with dialkylsilylene (dimethylsilylene), diarylsilylene (diphenylsilylene) or alkylarylsilylene (methylphenylsilylene) radicals.

[0066] When a cycloalkadienyl group is substituted, the substituents are especially chosen from C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, aryl and aralkyl groups. Two substituents which are in adjacent positions on the same cycloalkadienyl ring may be linked together, forming an aromatic or non-aromatic ring condensed on the said cycloalkadienyl ring. If the latter is a cyclopentadienyl ring, the resulting condensed cycle may be an indenyl, tetrahydroindenyl, fluorenyl or octahydrofluorenyl ring.

[0067] Moreover, at least one ligand L may be chosen from:

[0068] groups of formula:

[0069] —O—; —S—; —NR⁶—; or —PR⁶

[0070] (where R⁶ represents hydrogen or a group chosen from the silyl, alkyl or aryl groups, the latter two being optionally halogenated), one of the free valencies of which is linked to the transition metal M atom and the other free valency of which is linked to a divalent radical which is itself linked to a ligand L having a cycloalkadienyl backbone; and

[0071] groups of formula:

[0072] —OR⁷; —SR⁷; —NR⁷ ₂; or —PR⁷ ₂

[0073] (R⁷ having the same meaning as R⁶ above), the free valency of which is linked to a divalent radical which is itself linked to a ligand L having a cycloalkadienyl backbone;

[0074] examples of divalent radicals having been indicated above in the description of the agents carrying two cycloalkadienyl ligands.

[0075] Ligands L differing from those mentioned above may be chosen from:

[0076] hydrocarbon groups containing from 1 to 20 carbon atoms, such as linear or branched alkyl groups (such as methyl, ethyl, propyl, isopropyl and butyl); cycloalkyl groups (such as cyclopentyl and cyclohexyl); aryl groups (such as phenyl); alkaryl groups (such as tolyl); and aralkyl groups (such as benzyl);

[0077] alkoxy groups, such as methoxy, ethoxy, butoxy and phenoxy; and

[0078] halogens, such as fluorine, chlorine, bromine and iodine.

[0079] By way of examples, the metallocene catalyst may be chosen from the following compounds:

[0080] bis(cyclopentadienyl)dichlorozirconium (Cp₂ZrCl₂);

[0081] bis (indenyl) dichlorozirconium (Ind₂ZrCl₂);

[0082] bis (n-butylcyclopentadienyl) dichlorozirconium [(nBuCp)₂ZrCl₂];

[0083] ethylenebis(4,5,6,7-tetrahydro-1-indenyl) dichloro-zirconium [Et(THInd)₂ZrCl₂];

[0084] ethylenebis(indenyl)dichlorozirconium [Et (Ind)₂ZrCl₂];

[0085] isopropylidene(cyclopentadienyl, fluorenyl)-dichlorozirconium [iPr(Cp) (Flu) ZrCl₂];

[0086] isopropylidenebis(tert-butylcyclopentadienyl)-dichlorozirconium [iPr(tBuCp)₂ZrCl₂];

[0087] dimethylsilyl (3-tert-butylcyclopentadienyl, fluorenyl)dichlorozirconium;

[0088] dimethylsilylbisindenyldichlorozirconium [Me₂Si(Ind)₂ZrCl₂];

[0089] bis(cyclopentadienyl)dimethylzirconium;

[0090] bis(indenyl)dimethylzirconium (Ind₂ZrMe₂);

[0091] ethylenebis (4,5,6,7-tetrahydro-1-indenyl) dimethylzirconium;

[0092] ethylenebis(indenyl)dimethylzirconium;

[0093] isopropylidene(cyclopentadienyl, fluorenyl)-dimethylzirconium;

[0094] dimethylsilyl (3-tert-butylcyclopentadienyl, fluorenyl)dimethylzirconium;

[0095] bis(cyclopentadienyl)diphenylzirconium;

[0096] bis(cyclopentadienyl)dibenzylzirconium;

[0097] dimethylsilyl(tetramethylcyclopentadienyl, tert-butylamino)dichlorozirconium, the latter compound having the formula (CH₃)₂Si( (CH₃)₄C₅, (CH₃)₃ CN) ZrCl₂;

[0098] dimethylsilyl(tetramethylcyclopentadienyl, tert-butylamino)dimethyltitanium, this compound having the formula (CH₃)₂Si((CH₃)₄C₅, (CH₃)₃CN)Ti(CH₃)₂;

[0099] bis (cyclopentadienyl)dichlorotitanium;

[0100] ethylenebis(4,5,6,7-tetrahydro-1-indenyl)-dichlorotitanium;

[0101] ethylenebis(indenyl)dichlorotitanium;

[0102] isopropylidene(cyclopentadienyl, fluorenyl)-dichlorotitanium;

[0103] dimethylsilyl(3-tert-butylcyclopentadienyl, fluorenyl)dichlorotitanium;

[0104] bis(cyclopentadienyl)dimethyltitanium;

[0105] ethylenebis(4,5,6,7-tetrahydro-1-indenyl) dimethyl-titanium;

[0106] ethylenebis(indenyl)dimethyltitanium;

[0107] isopropylidene(cyclopentadienyl, fluorenyl)-dimethyltitanium;

[0108] dimethylsilyl(3-tert-butylcyclopentadienyl, fluorenyl) dimethyltitanium;

[0109] dimethylsilyl(tetramethylcyclopentadienyl, tert-butylamino)dichlorotitanium, the latter compound having the formula (CH₃)₂Si ((CH₃)₄C₅, (CH₃)₃CN)TiCl₂.

[0110] With regard to the cocatalysts (b), they are especially chosen from:

[0111] (b1) alkylaluminiums of formula (Ia):

Al(R⁸)₃   (Ia)

[0112] in which the R⁸ groups, which are identical or different, represent a substituted or unsubstituted alkyl, containing from 1 to 12 carbon atoms such as ethyl, isobutyl, n-hexyl and n-octyl; an alkoxy; an aryl; a halogen; hydrogen or oxygen; at least one R⁸ group representing an alkyl;

[0113] (b2) aluminium sesquihalides;

[0114] (b3) compounds of formula (IIIa) consisting of compounds of formula (III) as defined above, in which Y=Al; and

[0115] (b4) compounds of formula (IV) as defined above.

[0116] By way of examples of cocatalyst (b), mention may be made of methylaluminoxane, triisobutylaluminium and triethylaluminium.

[0117] As was mentioned above, the metallocene catalyst may be pre-impregnated on the activator support. This pre-impregnation may be carried out as follows:

[0118] The activator support is put into suspension, in a solvent chosen from aliphatic, alicyclic or aromatic hydrocarbons, with the metallocene. The operation is carried out between 0 and 140° C. for 1 hour to 10 hours. The proportion of metallocene represents between 0.01 and 20% by mass with respect to the activator support. At the end of the operation, the mixture is decanted in order to remove the supernatant liquid. The support is then washed several times, between 20 and 140° C., with a quantity of solvent of between 50 and 300 ml per gram of support.

[0119] Moreover, as already mentioned above, the metallocene (a) may have been subjected to prealkylation; if the activator support is pre-impregnated with the metallocene (a), this prealkylation may take place either before or after the pre-impregnation.

[0120] The prealkylation may be carried out using an alkylizing agent, such as an alkyllithium or an alkylmagnesium, the straight-chain or branched alkyl group having from 1 to 20 carbon atoms, under the following conditions:

[0121] The metallocene or the impregnated solid support are placed in a Schlenk tube containing from 10 to 50 ml of a solvent, chosen from aliphatic, alicyclic or aromatic hydrocarbons, per gram of support or per 10 milligrams of metallocene. The temperature of the mixture is taken to between −100 and 0° C. Between 1 and 5 mol of alkylizing agent per mole of metallocene are then introduced. After they have been introduced, the reaction mixture is left so as to come slowly back to room temperature. The complete operation lasts between 1 and 10 hours.

[0122] In the catalytic system according to the invention, the Al molar ratio of the cocatalyst (b1) or (b2) to the transition metal of the metallocene is especially from 1 to 10,000, in particular from 1 to 2000; and the Al molar ratio of the cocatalyst (b3) or (b4) to the transition metal of the metallocene (a) is especially from 1 to 10,000, in particular from 10 to 200. Moreover, the activator solid support is used especially in an amount ranging from 0.01 to 2000 mg, in particular from 0.01 to 200 mg, per μmole of metallocene catalyst.

[0123] The present invention also relates to a process for homopolymerizing or copolymerizing olefins, in suspension or in the gas phase, in the presence of a catalytic system as defined above.

[0124] The olefins which can be used for the polymerization (homopolymerization and copolymerization) are, for example, the olefins containing from two to twenty carbon atoms and, in particular α-olefins of this group. Mention may be made of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-octene, 1-hexene, 3-methyl-1-pentene, 3-methyl-1-butene, 1-decene and 1-tetradecene, or mixtures thereof as the olefin. In particular, the olefin is ethylene.

[0125] If the polymerization process is carried out in suspension, it may be performed in the following manner: a suspension in an inert medium, such as an aliphatic hydrocarbon, of the catalytic system is introduced into a reactor, the concentration of the metallocene (a) being from 0.5 μmol/l to 10 μmol/l, that of the cocatalyst (b) being from 0.01 to 5 mmol/l, the amount of activator solid support being from 0.5 to 1000 mg/l, and then the olefin or olefins are introduced at a pressure ranging from 1 to 250 bar, the (co)polymerization being carried out at a temperature ranging from −20° C. to 250° C. for a period of time ranging from 5 minutes to 10 hours.

[0126] It is possible to use n-heptane, n-hexane, isohexane, isopentane or isobutane as the aliphatic hydrocarbon.

[0127] The preferred conditions are as follows:

[0128] pressure ranging from 0.5 to 60 bar;

[0129] temperature ranging from 10° C. to a temperature slightly below the melting point of the polymer (5° C. below this melting point).

[0130] If the polymerization is carried out in the gas phase, it may be performed as follows: the olefin or olefins are injected at a pressure of 1-60 bar, at a temperature ranging from 10 to 110° C., into a reactor having a stirred bed and/or a fluidized bed of the catalytic system. In this case, the metallocene catalyst has been impregnated into the activator support and the cocatalyst is introduced by injection into the reactor or by impregnation of a solid charge injected into the reactor.

[0131] The aforementioned polymerization processes may involve a chain-transfer agent so as to control the melt flow index of the polymer to be produced. Hydrogen may be used as the chain-transfer agent, this being introduced in an amount which can range up to 90% and preferably lies between 0.01 and 60% in terms of moles of the olefin/hydrogen combination injected into the reactor.

[0132] If it is desired to have excellent morphological control of the polymer particles, it is recommended to carry out a suspension, or, preferably gas-phase prepolymerization step on the catalytic system of the invention and then to introduce the prepolymer particles thus obtained into the suspension or gas-phase. (co)polymerization process proper. The prepolymerization is carried out to a degree tailored to the polymerization process in which the prepolymer will subsequently be used.

[0133] The following examples illustrate the present invention without, however, limiting its scope. In these examples, the following abbreviations have been used for the (co)polymers prepared:

[0134] {overscore (M)}_(w)=weight-average molecular mass

[0135] {overscore (M)}_(n)=number-average molecular mass, these masses being determined by SEC.

[0136] {overscore (M)}_(w)/{overscore (M)}_(n)=polydispersivity

[0137] % mm=percentage of meso diads, determined by NMR.

[0138] The activator solid supports for the metallocene catalysts prepared have been denoted according to the following preparation steps: SiO₂/functionalization agent/O₂ (oxygenation)/F (fluorination).

[0139] The activities and productivities are regarded as zero when they are less than 10² g/mol.h and g/mol, respectively.

[0140] All the containers and reactors used were purged with argon and, unless otherwise specified, the syntheses were carried out in an argon atmosphere.

[0141] With regard to the (co)polymerization reactions, unless otherwise indicated, the concentrations are with respect to the quantity of solvent used for the (co)polymerization.

[0142] Agents used for functionalizing the silanol groups of the silica:

[0143] di (sec-butoxy) aluminoxytriethoxysilane,

(C₂H₅O)₃—Si—O—Al—(OC₄H₉)₂

[0144] MgBu₂=(n-butyl)(sec-butyl) magnesium

[0145] TEA=triethylaluminium.

[0146] Metallocene catalysts used:

[0147] Cp₂ZrCl₂, Ind₂ZrCl₂, Ind₂ZrMe₂, Me₂Si(Ind)₂ZrCl₂,

[0148] Et(Ind)₂ZrCl₂: defined above.

[0149] Cocatalysts used:

[0150] MAO=methylaluminoxane

[0151] TiBA=triisobutylaluminium

[0152] TEA=triethylaluminium.

[0153] In the expression for the activity (this is the maximum activity, unless otherwise mentioned) in g of (co)polymer/g_(cat).h and for the productivity in g of (co)polymer/g_(cat), g_(cat) means the mass of activator solid+mass of metallocene.

[0154] I—Polymerization of Ethylene

[0155] Pressure: 4 bar

[0156] Temperature: 80° C.

[0157] Suspension medium: 300 cm³ of heptane.

EXAMPLE 1

[0158] (a) Preparation of the Activator Solid Support SiO₂/Dibutoxyaluminoxytriethoxysilane/O₂/F

[0159] Silica having a specific surface area of 300 m²/g, sold under the name “GRACE 332” by Grace, is treated in dynamic vacuum according to the following temperature programme:

[0160] from 20° C. to 100° C. in 30 minutes;

[0161] from 100° C. to 130° C. in 30 minutes;

[0162] from 130° C. to 450° C. in 1 hour 30 minutes; and

[0163] a 450° C. hold for 2 hours.

[0164] This treatment gives a silica which contains 1 mmol of OH/g. 1 gram of the heat-treated silica is put into suspension in 20 cm³ of heptane. This suspension is treated with 846 mg of dibutoxyaluminoxytriethoxysilane (352.5 g/mol) at 50° C. for 1 hour. At the end of the reaction, 100 cm³ of heptane are added. After stirring for 10 minutes, the suspension is decanted in order to remove the supernatant liquid. The washing operation is repeated 3 times. After the final washing, the stock is dried for 1 hour at 100° C. in dynamic vacuum. This stock is then treated as a bed fluidized by argon according to the temperature programme:

[0165] from 20° C. to 130° C. in 1 hour;

[0166] from 130° C. to 450° C. in 1 hour;

[0167] a 450° C. hold for 1 hour;

[0168] from 450° C. to 20° C. in 2 hours.

[0169] This step is followed by a heat treatment identical to the previous one, but by fluidizing the stock with oxygen.

[0170] 62 mg of (NH₄)₂SiF₆ (178 g/mol) are then added. This mixture, gently fluidized using a stream of argon, undergoes the following heat treatment:

[0171] from 20° C. to 130° C. in 1 hour;

[0172] from 130° C. to 450° C. in 1 hour;

[0173] a 450° C. hold for 1 hour;

[0174] from 450° C. to 20° C. in 2 hours.

[0175] Solid support {circle over (1)} is thus obtained.

[0176] (b) Polymerization of ethylene

[0177] The following are placed in a 1 litre round-bottomed flask: 300 cm³ of heptane, 0.1 cm³ of an MAO solution (1.53 mol/l of aluminium in toluene), 17 mg of solid support compound {circle over (1)} and 0.9 μmol of Cp₂ZrCl₂. This suspension is injected into a 500 cm³ reactor. The polymerization temperature is 80° C. and the pressure of the ethylene is maintained at 4 bar for 60 minutes. 6.6 g of polyethylene is recovered, this having:

[0178] {overscore (M)}_(w)=227,000

[0179] {overscore (M)}_(n)=43,330

[0180] {overscore (M)}_(w)/{overscore (M)}_(n)=5.2

EXAMPLE 2

[0181] (a) Preparation of the Activator Solid Support SiO₁/MgBu₂/F

[0182] The silica used in this example is identical to that in Example 1 and underwent the same heat treatment. 4.6 g of this silica are put into suspension in 20 cm³ of heptane. This suspension is treated with 13.5 cm³ of a solution of MgBu in hexane (1 mole/l) at 50° C. for 1 hour. At the end of the reaction, 100 cm³ of heptane are added. After stirring for 10 minutes, the suspension is decanted in order to remove the supernatant liquid. The washing operation is repeated 3 times. After the final washing, the stock is dried for 1 hour at 100° C. in dynamic vacuum.

[0183] Next, 238 mg of (NH₄)₂SiF₆ are added. This mixture, gently fluidized with a stream of argon, undergoes the heat treatment defined at the end of point (a) in Example 1.

[0184] Solid support {circle over (2)} is thus obtained.

[0185] (b) Polymerization of Ethylene

[0186] This polymerization is carried out as in Example 1(b), except that 16 mg of solid support compound {circle over (2)} are used.

[0187] The results are given in Table 1.

EXAMPLE 3

[0188] (a) Preparation of the Activator Solid Support SiO₂/TEA/F

[0189] The silica used in this example is identical to that in Example 1 and underwent the same heat treatment. 1 g of this silica is put into suspension in 20 cm³ of heptane. This suspension is treated with 0.8 cm³ of TEA (1.5 mol/l in heptane) at 50° C. for 1 hour. At the end of the reaction, 100 cm³ of heptane are added. After stirring for 10 minutes, the suspension is decanted in order to remove the supernatant liquid. The washing operation is repeated 3 times. After the final washing, the stock is dried for 1 hour at 100° C. in dynamic vacuum.

[0190] Next, 62 mg of (NH₄)₂SiF₆ (178 g/mol) are added. This mixture, gently fluidized by a stream of nitrogen, undergoes the heat treatment defined at the end of point (a) of Example 1.

[0191] Solid support {circle over (3)} is thus obtained.

[0192] (b) Polymerization of Ethylene

[0193] This polymerization is carried out as in Example 1(b), except that 14 mg of solid support compound {circle over (3)} are used.

[0194] The results are also given in Table 1.

EXAMPLE 4 (COMPARATIVE EXAMPLE)

[0195] Polymerization of Ethylene in the Absence of an Activator Solid Support for a Metallocene Catalyst

[0196] This polymerization is carried out as in Example 1, except that a solid support compound is not used. The polyethylene obtained has the following characteristics:

[0197] {overscore (M)}_(w)=214,600

[0198] {overscore (M)}_(n)=30,940

[0199] {overscore (M)}_(w)/{overscore (M)}_(n)=6.9

[0200] The results are also given in Table 1. TABLE 1 Polymerization of ethylene Metallocene catalyst: Cp₂ZrCl₂ in an amount of 3 μmol/l Cocatalyst = MAO in an amount of 0.5 mmol/l Activator solid support for the Activity Productivity Activity Productivity catalyst (gPE/ (gPE/ (gPE/ (gPE/ Example (mg) mol Zr · h) mol Zr) g_(cat) · h) g_(cat)) Activation* 1 Solid 7.31 × 10⁶ 4.30 × 10⁶ 433.5 255 5.0 support {circle over (1)} (17) 2 Solid 2.19 × 10⁶ 1.36 × 10⁶ 147 91 1.5 support {circle over (2)} (16) 3 Solid 2.04 × 10⁶ 1.61 × 10⁶ 137 108 1.4 support {circle over (3)} (14) 4 — 1.46 × 10⁶ 0.89 × 10⁶ — — — (comparative)

EXAMPLE 5

[0201] An ethylene polymerization reaction is carried out under the conditions of Example 1(b), except that the MAO is replaced by 0.4 cm₃ of TiBA (1.4 mol/l in heptane, i.e. 2 mmol/l) and solid support {circle over (1)} has been used in an amount of 15 mg instead of 17 mg.

[0202] The results are as follows:

[0203] Activity (gPE/mol Zr.h): 0.90×10⁶

[0204] Productivity (gPE/mol Zr): 0.70×10⁶

EXAMPLE 6 (COMPARATIVE EXAMPLE)

[0205] An ethylene polymerization reaction is carried out as in Example 5, except that no activator solid support for the catalyst is used.

[0206] The activity and productivity are zero.

EXAMPLE 7

[0207] Example 5 is repeated except that the TiBA is replaced by 1.0 cm³ of TEA (1.5 mol/l in heptane, i.e. 5 mmol/l).

[0208] The results are as follows:

[0209] Activity (gPE/mol Zr.h): 0.49×10⁶

[0210] Productivity (gPE/mol Zr): 0.36×10⁶

EXAMPLE 8 (COMPARATIVE EXAMPLE)

[0211] An ethylene polymerization reaction is carried out as in Example 7, except that no activator solid support compound for the catalyst is used.

[0212] The results are as follows:

[0213] Activity (gPE/mol Zr.h): 1100

[0214] Productivity (gPE/mol Zr): 880

EXAMPLE 9

[0215] An ethylene homopolymerization reaction is carried out as in Example 5, except that the 0.9 μmol of Cp₂ZrCl₂ are replaced by 0.9 μmol of Ind₂ZrCl₂.

[0216] The results are given in Table 2.

EXAMPLE 10

[0217] An ethylene homopolymerization reaction is carried out as in Example 9, except that 0.1 mmol/l of TiBA are used as cocatalyst.

[0218] The results are given in Table 2.

EXAMPLE 11 (COMPARATIVE EXAMPLE)

[0219] An ethylene homopolymerization reaction is carried out as in Example 9, except that no activator solid support compound for the catalyst is used.

[0220] The results are given in Table 2. TABLE 2 Polymerization of ethylene Metallocene catalyst: Ind₂ZrCl₂ in an amount of 3 μmol/l Activator solid support for the catalyst (apart from Example 11) = solid support 1 in an amount of 10 mg Cocatalyst Activity Productivity Example (mmol/l) (gPE/mol Zr · h) (gPE/mol Zr)  9 TiBA 1.06 × 10⁶ 6.67 × 10⁵ (2) 10 TiBA 6.72 × 10⁶ 4.08 × 10⁵ (0.1)   11 TiBA 1.89 × 10⁵ 1.57 × 10⁵ (comparative) (2)

EXAMPLE 12

[0221] An ethylene homopolymerization reaction is carried out as in Example 5, except that the 0.9 μmol of Cp₂ZrCl₂ are replaced by 0.9 μmol of Ind₂ZrMe₂.

[0222] The results are given in Table 3.

EXAMPLES 13 AND 14

[0223] An ethylene homopolymerization reaction is carried out as in Example 12, except that 0.5 and 0.1 mmol/l of TiBA are used as cocatalyst, respectively.

[0224] The results are given in Table 3.

EXAMPLE 15 (COMPARATIVE EXAMPLE)

[0225] An ethylene homopolymerization reaction is carried out as in Example 12, except that no activator solid support compound for the catalyst is used.

[0226] The results are given in Table 3. TABLE 3 Polymerization of ethylene Metallocene catalyst: Ind₂ZrMe₂ in an amount of 3 μmol/l Activator solid support for the catalyst (apart from Example 15) = solid support 1 in an amount of 75 mg Cocatalyst Activity Productivity Example (mmol/l) (gPE/mol Zr · h) (gPE/mol Zr) 12 TiBA 2.37 × 10⁶ 1.38 × 10⁶   (2) 13 TiBA 2.46 × 10⁶ 1.40 × 10⁶ (0.5) 14 TiBA 1.32 × 10⁷ 7.37 × 10⁶ (0.1) 15 TiBA 0 0 (comparative)   (2)

EXAMPLE 16

[0227] An ethylene homopolymerization reaction is carried out as in Example 5, except that the 0.9 μmol of Cp₂ZrCl₂ are replaced by 0.9 μmol of Me₂Si(Ind)₂ZrCl₂ and the TiBA cocatalyst is used in an amount of 5 mmol/l.

[0228] The results are as follows:

[0229] Activity (gPE/mol Zr.h): 2.02×10⁶

[0230] Productivity (gPE/mol Zr): 1.88×10⁶.

EXAMPLE 17 (COMPARATIVE EXAMPLE):

[0231] An ethylene homopolymerization reaction is carried out as in Example 16, except that no catalyst activator solid support compound is used.

[0232] The activity and productivity are zero.

EXAMPLE 18

[0233] (a) Preparation of the Activator Solid Support: Solid Support {circle over (1)}

[0234] The procedure is carried out as in Example 1(a).

[0235] (b) Pre-impregnation of the Solid Support with Cp₂ZrCl₂

[0236] 417 mg of solid support {circle over (1)} are then put into suspension in 50 cm³ of toluene with 70 mg of Cp₂ZrCl₂ at 70° C. for 15 hours. At the end of the operation, the mixture is decanted in order to remove the supernatant liquid. 4 operations of washing with toluene at 70° C. for 15 minutes are carried out. Each washing operation is interrupted by a settling operation followed by removal of the supernatant liquid. Finally, a drying operation is carried out at 40° C. for 40 minutes.

[0237] Solid support {circle over (1)}′ is obtained.

[0238] (c) Polymerization of Ethylene

[0239] The following are placed in a 1 litre round-bottomed flask: 300 cm³ of heptane, 0.10 cm³ of MAO (1.53 mol/l of aluminium in toluene) and 10 mg of pre-impregnated solid support {circle over (1)}′. This suspension is injected into a 500 cm³ reactor. The polymerization temperature is 80° C. and the pressure of the ethylene is 4 bar. After 60 minutes, 2.2 g of polyethylene are recovered.

[0240] The results obtained are given in Table 4.

EXAMPLES 19 and 20

[0241] The procedure as in Example 18 is carried out except that the activator solid supports {circle over (2)} and {circle over (3)}, were used to obtain the solid supports {circle over (2)}′ and {circle over (3)}′, respectively.

[0242] In Example 19, 1.19 g of activator solid support {circle over (2)} and 55 mg of Cp₂ZrCl₂ were used.

[0243] In Example 20, 877 mg of activator solid support {circle over (3)} and 80 mg of Cp₂ZrCl₂ were used.

[0244] The results are given in Table 4. TABLE 4 Polymerization of ethylene Metallocene catalyst: Cp₂ZrCl₂ Cocatalyst: MAO in an amount of 0.5 mmol/l. % of Zr of the metallocene Mass of catalyst catalyst or impregnated activator into solid support Ex- the solid impregnated Activity Activity ample support (mg) (gPE/mol Zr · h) (gPE/g_(cat) · h) 18 0.93 Solid support {circle over (1)}′ 4.71 × 10⁶ 480 (10) 19 1.05 Solid support {circle over (2)}′ 6.08 × 10⁶ 700 (10) 20 0.45 Solid support {circle over (3)}′ 1.43 × 10⁷ 220  (9)

EXAMPLE 21

[0245] (a) Preparation of the Activator Solid Support

[0246] The procedure is carried out as for solid support {circle over (2)} in Example 2(a).

[0247] (b) Prealkylation of the Metallocene

[0248] 80 mg of Cp₂ZrCl₂ are dissolved in 20 cm³ of toluene. The temperature of the solution is then lowered to −80° C. 0.35 cm³ of methyllithium (1.6 mol/l in ether) are then added drop by drop. After the addition has been completed, the reaction mixture is left to return slowly to room temperature. After settling, the supernatant liquid is removed.

[0249] (c) Pre-impregnation

[0250] Solid support {circle over (2)} from step (a) and the supernatant liquid from step (b) are mixed in 30 cm³ of heptane. The rest of the pre-impregnation operation is identical to that in Example 18(b).

[0251] (d) Polymerization of Ethylene

[0252] The ethylene polymerization is carried out as in Example 18(c).

[0253] The results obtained are as follows:

[0254] % of Zr impregnated into the solid support: 1.60

[0255] Cocatalyst: MAO in an amount of 0.5 mmol/l

[0256] Activity (gPE/mol Zr.h): 2.85×10⁶

[0257] Activity (gPE/g_(cat).h) : 500.

EXAMPLE 22

[0258] (a) Preparation of the Activator Solid Support

[0259] The procedure is carried out as for solid support {circle over (2)} in Example 2 (a).

[0260] (b) Pre-impregnation of the Metallocene

[0261] The procedure is carried out as in Example 18 (b).

[0262] (c) Prealkylation of the Metallocene

[0263] The pre-impregnated solid support is put into suspension in 20 cm³ of toluene. The temperature of the suspension is then lowered to −80° C. 0.14 cm³ of methyllithium (1.6 mol/l in ether) are then added drop by drop. After completing the addition, the reaction mixture is left to come back slowly to room temperature. After settling, the supernatant liquid is removed. The solid support is dried at 40° C. for 30 minutes.

[0264] (d) Polymerization

[0265] The ethylene polymerization is carried out as in Example 18 (c).

[0266] The results are as follows:

[0267] % of Zr impregnated into the solid support: 0.60

[0268] Cocatalyst: MAO in an amount of 0.5 mmol/l

[0269] Activity (gPE/mol Zr.h): 3.64×10⁶

[0270] Activity (gPE/g_(cat).h): 240.

EXAMPLE 23

[0271] The procedure is carried out as in Example 1, except that the TiBA cocatalyst is used instead of the MAO cocatalyst, again in an amount of 0.5 mmol/l.

[0272] The results are given in Table 6.

EXAMPLES 24 to 29 (COMPARATIVE EXAMPLES)

[0273] Example 23 was repeated, except that silica SiO₂ calcined according to the technique in Example 1(a) or a silica modified in a different way from that according to the present invention, namely by fluorination of SiO₂ or of SiO₂/dibutoxyaluminoxy-triethoxysilane with (NH₄)₂SiF₆ in the case of Examples 25 and 27, respectively; by stopping at the SiO₂/dibutoxyaluminoxytriethoxysilane and SiO₂/dibutoxyaluminoxytriethoxysilane/O₂ stages, respectively, in the case of Examples 26 and 28, respectively; and by chlorination of SiO₂/dibutoxyaluminoxytriethoxysilane/O₂ using NH₄Cl in the case of Example 29, was used as the activator solid support.

[0274] The operating methods in Examples 25, 27 and 29 may be summarized as follows:

EXAMPLE 25

[0275] The silica of Example 1 which has undergone the initial heat treatment (silica containing 1 mmol of OH/g) is used.

[0276] 140 mg of (NH₄)₂SiF₆ are added to 2 g of this silica and the mixture, which is gently fluidized by a stream of argon, is made to undergo the heat treatment indicated at the end of. Example 1(a).

EXAMPLE 27

[0277] The procedure is carried out as in Example 1(a) except that 62 mg of (NH₄)₂SiF₆ are added to the stock which is functionalized by dibutoxyaluminoxy-triethoxysilane and dried for 1 hour at 100° C. in dynamic vacuum, and the mixture, which is gently fluidized by a stream of argon, is made to undergo the heat treatment indicated at the end of Example 1(a). The oxygen heat treatment in Example 1(a) is not carried out here.

EXAMPLE 29

[0278] The procedure is carried out as in Example 1(a) except that (NH₄)₂SiF₆ is replaced by NH₄Cl.

[0279] The results are also given in Table 5. TABLE 5 Polymerization of ethylene Metallocene catalyst: CpZrCl₂ in an amount of 3 μmol/l Cocatalyst: TiBA in an amount of 0.5 mmol/l Amount of activator solid support Productivity Example Activator solid support (gPE/mol Zr) 23 SiO₂/dibutoxyaluminoxytriethoxysilane/O₂/F 6.20 × 10⁵ 24 (comp.) SiO₂ 0 25 (comp.) SiO₂/F 0 26 (comp.) SiO₂/dibutoxyaluminoxytriethoxysilane 0 27 (comp.) SiO₂/dibutoxyaluminoxytriethoxysilane/F 9.76 × 10⁴ 28 (comp.) SiO₂/dibutoxyaluminoxytriethoxysilane/O₂ 0 29 (comp.) SiO₂/dibutoxyaluminoxytriethoxysilane/O₂/ 0 Cl

[0280] II—Polymerization of Propylene

[0281] Pressure: 4 bar

[0282] Temperature: 40° C.

[0283] Suspension medium: 500 cm³ of heptane.

EXAMPLE 30

[0284] (a) Preparation of solid support {circle over (1)}

[0285] The procedure is carried out as in Example 1(a).

[0286] (b) Polymerization of Propylene

[0287] The following are placed in a 1 litre round-bottomed flask: 500 cm³ of heptane, 0.16 cm³ of MAO (1.53 mol/l of aluminium in toluene), 17 mg of the solid support compound obtained at (a) and 1.5 μmol of EtInd₂ZrCl₂ (5.56×10⁻⁴ mol/l in toluene). This suspension is injected into the 1 l reactor. The polymerization temperature is 40° C. and the propylene pressure is 4 bar. After 75 minutes, 24 g of polypropylene with a melting point of 137.6° C. and a % mm of 89.6 are recovered.

[0288] The results are given in Table 6.

EXAMPLE 31 (COMPARATIVE EXAMPLE)

[0289] The procedure is carried out as in Example 30, except that no catalyst activator solid support is used.

[0290] The results are also given in Table 6.

EXAMPLE 32

[0291] The procedure is carried out as in Example 30, except that the 1.5 μmol of Et(Ind)₂ZrCl₂ are replaced by 1.5 μmol of Me₂Si(Ind)₂ZrCl₂.

[0292] The results are also given in Table 6.

EXAMPLE 33 (COMPARATIVE EXAMPLE)

[0293] The procedure is carried out as in Example 32, except that no catalyst activator solid support is used.

[0294] The results are also given in Table 6. TABLE 6 Metallocene catalyst used in an amount of 3 μmol/l Cocatalyst: MAO in an amount of 0.5 mmol/l Activator solid support Activity Metallocene for the (gPP/mol Productivity Activity Productivity T_(melting) Example catalyst catalyst (mg) Zr · h) (gPP/mol Zr) (gPP/g_(cat) · h) (gPP/g_(cat)) {overscore (M)}_(w) {overscore (M)}_(n) {overscore (M)}_(w)/{overscore (M)}_(n) (° C.) % mm 30 Et(Ind)₂ZrCl₂ Solid support {circle over (1)} 1.67 × 10⁷ 1.17 × 10⁷ 1582 1108 37890 16970 2.23 137.6 89.6 (16) 31 Et(Ind)₂ZrCl₂ — 1.04 × 10⁷ 0.81 × 10⁷ — — 38150 19270 1.98 135.8 89.8 (comp.) 32 Me₂(Ind)₂ZrCl₂ Solid support {circle over (1)} 0.89 × 10⁷ 0.37 × 10⁷ 974 405 62830 27930 2.25 145.0 92.8 (16) 33 Me₂(Ind)₂ZrCl₂ — 0.44 × 10⁷ 0.34 × 10⁷ — — 61740 26670 2.31 144.3 90.9 (comp.)

[0295] III—Ethylene-Hexene Copolymerization

EXAMPLE 34

[0296] The following are introduced in succession into a 1 litre round-bottomed flask: 300 cm³ of heptane, 5 cm³ of 1-hexene, 0.15 cm³ of TiBA (1 mol/l in heptane), 18 mg of solid support {circle over (1)} and 1×10⁻⁷ mol of Et(Ind)₂ZrCl₂. This suspension is introduced into a 500 cm³ reactor put under an inert atmosphere. After the suspension has been introduced, ethylene is gradually introduced with the temperature rise, reaching 4 bar at 80° C.

[0297] After polymerizing for 30 minutes, 17.1 g of copolymer having 6.9% of hexene by weight (infrared analysis) and a melting point of 113° C. are recovered.

[0298] The results are given in Table 7.

EXAMPLE 35 (COMPARATIVE EXAMPLE)

[0299] The procedure is carried out as in Example 34, except that no activator solid support is used and the metallocene catalyst is used in an amount of 3 μmol/l and the TiBA is used in an amount of 1 mmol/l.

[0300] No polymer is recovered (cf. Table 7).

EXAMPLE 36

[0301] The following are added in succession to a 1 litre round-bottomed flask: 300 cm³ of heptane, 5 cm³ of 1-hexene and 0.13 cm³ of TiBA (1 mol/l in heptane).

[0302] 22 mg of solid support {circle over (1)} and 0.2 cm³ of TiBA are introduced into a 50 cm³ round-bottomed flask and, after stirring for 5 minutes, 1.5×10⁻⁷ mol of Et(Ind)₂ZrCl₂ dissolved in. toluene are introduced.

[0303] The contents of the 50 cm³ flask is introduced into the 500 cm³ flask. This is all then introduced into the polymerization reactor. The experiment takes place at 80° C. with an ethylene pressure of 4 bar. After polymerizing for 30 minutes, 20.2 g of polymer are obtained.

[0304] The results are given in Table 7.

EXAMPLE 37 (COMPARATIVE EXAMPLE)

[0305] The procedure is carried out as in Example 35, except that the metallocene catalyst is used in an amount of 0.5 μmol/l and the TiBA is replaced by MAO used in an amount of 0.5 mmol/l, maintaining the proportions of aluminium.

[0306] 14.6 g of copolymer are recovered after polymerizing for 30 minutes.

[0307] The results are also given in Table 7. TABLE 7 Copolymerization of ethylene and 1-hexene Ethylene pressure = 4 bar Temperature = 80° C. Suspension medium = 300 cm³ of heptane Productivity after μmol/l of Activator solid 30 minutes Et(Ind)₂ZrCl₂ support for the Cocatalyst (gCOPO/mol Example catalyst catalyst (mg) (mmol/l) Zr) 34 0.5 Solid support {circle over (1)} TiBA 1.71 × 10⁶ (18) (0.5) 35 3 — TiBA 0 (comp.)   (1) 36 0.5 Solid support {circle over (1)} TiBA 1.34 × 10⁶ (22) (0.5) 37 0.5 — MAO 9.73 × 10⁷ (comp.) (0.5)

[0308] Although the invention has been described in conjunction with specific embodiments, it is evident that many alternatives and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, the invention is intended to embrace all of the alternatives and variations that fall within the spirit and scope of the appended claims. The above references are hereby incorporated by reference. 

1. Activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminium and/or magnesium Lewis-acid sites of formula:

groups coming from a functionalization agent having reacted with —OH radicals carried by the base particles of the support, the functionalization reaction having been followed by a fluorination reaction:
 2. Support according to claim 1, characterized in that the mineral oxides are chosen from silica, alumina and mixtures thereof.
 3. Support according to either of claims 1 and 2, characterized in that the particles include pores having a diameter ranging from 7.5 to 30 nm.
 4. Support according to one of claims 1 to 3, characterized in that the particles have a porosity ranging from 1 to 4 cm³/g.
 5. Support according to one of claims 1 to 4, characterized in that the particles have a specific surface area ranging from 100 to 600 m²/g.
 6. Support according to one of claims 1 to 5, characterized in that they have an average diameter ranging from 1 to 100 μm.
 7. Support according to one of claims 1 to 6, characterized in that the particles have, on their surface, from 0.25 to 10, especially from 0.5 to 4, of the said at least partially fluorinated aluminium and/or magnesium Lewis-acid sites per nm².
 8. Support according to one of claims 1 to 7, characterized in that the said at least partially fluorinated aluminium and/or magnesium Lewis-acid sites are formed by the reaction of —OH radicals carried by the support base particles with at least one functionalization agent chosen from: compounds of formula (I): Al(R¹)₃   (I) in which the R¹ groups, which are identical or different, each represent a C₁-C₂₀ alkyl group; compounds of formula (II): Mg(R²)₂   (II) in which the R² groups, which are identical or different, each represent a C₁-C₂₀ alkyl group; and compounds of formula (III):

in which: the R³ groups, which are identical or different, each represent a C₁-C₁₂ alkyl group or a C₁-C₁₂ alkoxy group; the R⁴ groups, which are identical or different, each represent a C₁-C₁₂ alkyl group or a C₁-C₁₂ alkoxy group; Y represents Al or Si, m having a value of 2 if Y=Al and 3 if Y=Si; and n has a value of 0 or is an integer from 1 to 40, n preferably having a value of 0 or being an integer from 1 to 20; compounds of formula (IV):

in which: the R⁵ groups each represent a C₁-C₈ alkyl group; and p is an integer from 3 to 20, the said functionalization reaction having been followed by a fluorination reaction.
 9. Support according to claim 8, characterized in that compound (I) is triethylaluminium.
 10. Support according to claim 8, characterized in that compound (II) is (n-butyl) (sec-butyl)magnesium.
 11. Support according to claim 8, characterized in that compound (III) is dibutoxyaluminoxytriethoxysilane (C₂H₅O)₃Si —O—Al—(OC₄H₉)₂, tetraisobutyldialuminoxane (iBu)₂Al—O—Al (iBu)₂ and linear alkylaluminoxane oligomers, in particular those in which R³ and R⁴ are methyl groups.
 12. Support as defined in one of claims 1 to 11, pre-impregnated with a metallocene catalyst, the said metallocene catalyst having been subjected, if required, to a prealkylation treatment carried out before or after the said support has been pre-impregnated.
 13. Process for preparing an activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that a group of support particles for a solid catalytic component, which are formed from. at least one porous mineral oxide and carry, on the surface, —OH radicals, undergoes functionalization by using a functionalization agent capable of grafting aluminium and/or magnesium Lewis-acid sites on the said particles; the said support particles thus grafted are then subjected to a fluorination treatment.
 14. Process according to claim 13, characterized in that the mineral oxides are chosen from silica, alumina and mixtures thereof.
 15. Process according to either of claims 13 and 14, characterized in that particles which include pores having a diameter ranging from 7.5 to 30 nm are used.
 16. Process according to one of claims 13 to 15, characterized in that particles having a porosity ranging from 1 to 4 cm³/g are used.
 17. Process according to one of claims 13 to 16, characterized in that particles having a specific surface area ranging from 100 to 600 m²/g are used.
 18. Process according to one of claims 13 to 17, characterized in that particles having an average diameter ranging from 1 to 100 μm are used.
 19. Process according to one of claims 14 to 18, characterized in that particles having, on their surface, ranging from 0.25 to 10, especially ranging from 0.5 to 4, of the said —OH radicals per nm² are used.
 20. Process according to one of claims 13 to 19, characterized in that a functionalization agent as defined in one of claims 8 to 11 is used.
 21. Process according to one of claims 13 to 20, characterized in that the functionalization is carried out by treating a suspension of the said particles in a solvent medium with the said functionalization agent at a temperature ranging from −100 to +150° C. for a period of time ranging from 1 minute to 12 hours, and then by recovering the grafted particles after washing.
 22. Process according to one of claims 13 to 21, characterized in that from 0.5 to 20 mmol of functionalization agent per g of particles are used.
 23. Process according to one of claims 13 to 22, characterized in that after the functionalization, a heat treatment in an inert gas is carried out, preferably in a bed fluidized by the said inert gas, the said treatment being intended to remove the alkoxy groups present on the surface.
 24. Process according to one of claims 13 to 23, characterized in that, prior to the fluorination treatment, an oxidation treatment is carried out which consists, in particular, of a heat treatment in a bed fluidized by oxygen.
 25. Process according to one of claims 13 to 24, characterized in that the fluorination treatment is carried out by bringing the functionalized support particles into contact with gaseous hydrofluoric acid, if necessary after heat treatment in an inert gas and/or after oxidation, especially in an amount of from 1 to 5% by weight, in particular 3 to 5% by weight, of fluorine with respect to the said support particles, this contacting step being carried out for a period of time ranging from 1 minute to 24 hours, at a temperature ranging from 20 to 800° C.
 26. Process according to one of claims 13 to 24, characterized in that the fluorination treatment is carried out by (NH₄)₂SiF₆, by mixing the functionalized support particles, if necessary after heat treatment in an inert gas and/or after oxidation, with powdered (NH₄)₂SiF₆, especially in an amount ranging from 1 to 5% by weight, in particular 3 to 5% by weight, of fluorine with respect to the said support particles, and then by gently fluidizing the aforementioned mixture with an inert gas and by carrying out a heat treatment at a temperature of. approximately 300 to 500° C. for approximately 1 to 10 hours.
 27. Catalytic system for the polymerization of olefins, comprising: (a) a metallocene catalyst, which has, if required, been subjected to a prealkylation treatment; (b) a cocatalyst; and (c) an activator solid support for metallocene, as defined in one of claims 1 to 11 or prepared by the process as defined in one of claims 13 to 26, it being possible for the cocatalyst (b) to be absent if the metallocene catalyst (a) has been prealkylated, it being possible for the support (c) to have been impregnated with the metallocene catalyst (a), which catalyst has, if required, been subjected to a prealkylation treatment carried out either before or after the said support has been pre-impregnated.
 28. Catalytic system according to claim 27, characterized in that the metallocene catalyst (a) is chosen from compounds of formula (V): ML_(x)  (V) in which: M represents a transition metal belonging to Group 4b of the Periodic Table of Elements; L represents a ligand coordinated to the transition metal, at least one ligand L being a group having a cycloalkadienyl-type backbone; and x is equal to the valency of the transition metal, the ligands L, the number of which is equal to the valency of the transition metal M, being identical or different; when compound (V) contains at least two groups having a cycloalkadienyl-type backbone, it being possible for at least two of these groups to be linked together by a divalent radical; when a group having a cycloalkadienyl backbone is substituted, it being possible for the substituents to be chosen from C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, aryl and aralkyl groups, it being possible for two substituents lying in adjacent positions on the same cyclopentadienyl ring to be linked together, forming an aromatic or non-aromatic ring condensed on the said cycloalkadienyl ring, and, if the latter is a cyclopentadienyl ring, it being possible for the resulting condensed ring to be an indenyl, tetrahydroindenyl, fluorenyl or octahydrofluorenyl ring; it being possible for at least one ligand L to be chosen from groups of formula —O—; —S—; —NR⁶—; or —PR⁶ (where R⁶ represents hydrogen or a group chosen from silyl, alkyl or aryl groups, the latter two optionally being halogenated), one of the free valencies of which is linked to the transition metal M atom and the other free valency of which is linked to a divalent radical which is itself linked to a ligand L having a cycloalkadienyl backbone; and groups of formula —OR⁷; —SR⁷; —NR⁷ ₂; or —PR⁷ ₂ (R⁷ having the same meaning as R⁶ above), the free valency of which is linked to a divalent radical which is itself linked to a ligand L having a cycloalkadienyl backbone; it being possible for ligands L differing from those defined above to be chosen from hydrocarbon groups containing from 1 to 20 carbon atoms, alkoxy groups and halogens.
 29. Catalytic system according to either of claims 27 and 28, characterized in that the cocatalyst (b) is chosen from: (b1) alkylaluminiums of formula (Ia) Al(R⁸)₃   (Ia) in which the R⁸ groups, which are identical or different, represent a substituted or unsubstituted alkyl, containing from 1 to 12 carbon atoms; an alkoxy; an aryl; a halogen; hydrogen or oxygen; at least one R⁸ group representing an alkyl; (b2) aluminium sesquihalides; (b3) compounds of formula (IIIa) consisting of compounds of formula (III) as defined in claim 8, in which Y=Al; and (b4) compounds of formula (IV) as defined in claim
 8. 30. Catalytic system according to claim 29, characterized in that the cocatalyst (b) is chosen from methylaluminoxane, triisobutylaluminium and triethylaluminium.
 31. Catalytic system according to one of claims 27 to 30, characterized in that the Al molar ratio of the cocatalyst (b1) or (b2) to the transition metal of the metallocene is from 1 to 10,000, in particular from 1 to 2000; and the Al molar ratio of the cocatalyst (b3) or (b4) to the transition metal of the metallocene (a) is from 1 to 10,000, in particular from 10 to
 200. 32. Catalytic system according to one of claims 27 to 31, characterized in that the activator solid is used in an amount ranging from 0.01 to 2000 mg, in particular from 0.01 to 200 mg, per μmole of metallocene catalyst.
 33. Process for homopolymerizing or copolymerizing olefins, in suspension or in the gas phase, in the presence of a catalytic system as defined in one of claims 27 to
 32. 34. Process according to claim 33, characterized in that C₂-C₂₀ olefins, in particular α-olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-octene, 1-hexene, 3-methyl-1-pentene, 3-methyl-1-butene, 1-decene and 1-tetradecene, are used.
 35. Process according to claim 34, characterized in that the olefin to be (co)polymerized is ethylene.
 36. Process according to one of claims 33 to 35, carried out in suspension, characterized in that a suspension in an inert medium, such as an aliphatic hydrocarbon, of the catalytic system is introduced into a reactor, the concentration of the metallocene (a) being from 0.5 μmol/l to 10 μmol/l, that of the cocatalyst (b) being from 0.01 to 5 mmol/l, the amount of activator solid support being from 0.5 to 1000 mg/l, and then the olefin or olefins are introduced at a pressure ranging from 1 to 250 bar, the (co)polymerization being carried out at a temperature ranging from −20° C. to 250° C. for a period of time ranging from 5 minutes to 10 hours.
 37. Process according to claim 36, characterized in that the olefin or olefins are introduced at a pressure ranging from 0.5 to 60 bar and the operation is carried out at a temperature ranging from 10° C. to a temperature slightly below the melting point of the polymer.
 38. Process according to one of claims 33 to 35, carried out in the gas phase, characterized in that the olefin or olefins are injected at a pressure of 1-60 bar, at a temperature ranging from 10 to 110° C., into a reactor having a stirred bed and/or a fluidized bed of the catalytic system.
 39. Process according to one of claims 33 to 38, characterized in that the operation is carried out in the presence of a chain-transfer agent, such as hydrogen.
 40. Process according to one of claims 33 to 39, characterized in that a suspension or, preferably, gas-phase prepolymerization step is firstly carried out on the catalytic system as defined in one of claims 27 to 32 and then the prepolymer particles thus obtained are introduced into the suspension or gas-phase (co)polymerization process proper. 